Conventionally, as a vinyl silane compound having two vinylsilyl groups in one molecule (particularly, a vinyldiorganosilyl group such as a vinyldimethylsilyl), there have been known, for example, 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 1,3-divinyl-1,1,3,3-tetraphenyldisiloxane and dimethylpolysiloxane with both molecular chain ends blocked by dimethylvinylsiloxy groups. Since these compounds have vinylsilyl groups, they can be subjected to hydrosilylation addition reactions with hydrosilane and organohydrogenpolysiloxane. Particularly, when there are used a bifunctional vinyl silane compound having two vinylsilyl groups in one molecule; and a bifunctional organohydrogenpolysiloxane having two silicon atom-bonded hydrogen atoms (SiH groups) in one molecule, polymerization reaction progresses (i.e. as a result of a chain-extending reaction progressing due to a continuous hydrosilylation addition reaction), thereby making it possible to obtain an organic silicon resin having a molecular weight (polymerization degree) that is high to a certain extent.
However, most of these known vinyl silane compounds generally have vinylsilyl groups that are bonded together by siloxane bonds, which in fact only allows properties derived from siloxane bonds to be imparted to an organic silicon resin (Patent documents 1 and 2; and Non-patent document 1).